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In invertebrates, the prophenoloxidase (proPO) pathway is involved in the phenol-like antioxidant production against invading pathogens. Overproduction of melanin and phenolic substances leads to the disruption of hemocytes (own host cells); therefore, there is a prerequisite to regulate the antioxidant production, which is performed by the proteases and proPO-associated cell adhesion protein peroxinectin (PX). PX is a macromolecular structure consisting of protein involved in the proPO pathway, which is a potential target in the regulatory mechanism in crustaceans. In the proPO cascade, pattern recognition proteins initiate the proPO cascade by the consequent reaction, and PX is involved in the key step in the regulatory mechanism of phenoloxidase enzyme synthesis. In the present study, Indian white shrimp Fenneropenaeus indicus PX ( Fein-PX) gene sequence was used. Upregulation of Fein-PX was determined using immunostimulants β-glucan (agonists) and examined its expression by quantitative RT-PCR. To find the downregulation or negative regulation of Fein-PX, inhibitors were screened, and its 3D model provides molecular insights into the rationale inhibitor design for developing an effective molecule against Fein-PX. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A full-length cDNA of a β-glucan binding protein ( β-GBP) gene was identified from the mangrove crab Episesarma tetragonum. The open reading frame of the E. tetragonum β-GBP ( Epte β-GBP) is 1,167 bp long, encoding a polypeptide of 389 amino acids. The deduced amino acid sequence of Epte β-GBP gene has conserved a potential recognition motif for β-1,3 linkages of polysaccharides and putative RGD (Arg-Gly-Asp) cell adhesion sites. Phylogenetic analysis of the Epte β-GBP gene showed the similarity with β-GBPs of other crustaceans and arthropods. Quantitative RT-PCR results showed the upregulation of Epte β-GBP gene expression in E. tetragonum hemocytes following a 12-H challenge in response to β-glucan (β-G). Epte β-GBP was involved in the regulation and activation of the prophenoloxidase cascade. A three-dimensional structure of active Epte β-GBP was modeled by homology modeling and refined with molecular dynamics simulations. A structural aspect of the protein is discussed based on experimental and theoretical results obtained. [ABSTRACT FROM AUTHOR]